Lawinenlagebericht

Purcells

Jan 19 – 20, 2012Avalanche Canada
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Archiviert · abgelaufen 15 years ago

Lawinengefahr

Sat
Sun
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–3
    Be alert for wind slabs behind ridges and ribs, especially on east and north-facing slopes.

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely - Possible
    Größe
    4–7
    Two layers to watch: 1. Buried surface hoar, most likely triggered on steep, unsupported slopes amongst the trees. 2. Basal facets, triggerable from thin snowpack areas or by a very heavy load (cornice fall, airborne sled). Avalanches could be large.

Snowpack Summary

Recent storm snow is settling slowly with cold temperatures. Winds have recently created slabs in exposed features. The mid-December surface hoar/facet persistent weakness, now down around 50cm on the eastern side of the range and as deep as 180cm on the western side, is still causing operators concern, especially in shallow snowpack areas. Recent snowpack tests show moderate to hard, sudden planar results on this layer. The consequences of a failure on this layer would be large. Facets and depth hoar exist at the base of the snowpack.

Confidence

Fair - Timing of incoming weather is uncertain on Friday

Weather Forecast

Friday: Moderate to heavy snowfall starting on Friday afternoon. 10-15cm, with 20cm possible on western slopes. Freezing level at valley bottom for most of the day. Winds increasing to strong westerlies by afternoon.Saturday: Snow continuing, with a further 10-20cm expected (most in the southern part of the region and on western slopes). Freezing level rising briefly to around 1000m on Saturday morning. Westerly winds.Sunday: Light snow. Freezing level valley floor.

Avalanche Summary

Explosives testing triggered many size 1-3.5 slabs in the central Purcells. All of the observed avalanches failed within the storm snow, with the exception of a couple of avalanches started by large cornices dropping onto the slope. In these cases, one failed at ground/glacier ice and one on a facet layer.

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